1. Technical Field
The present invention relates to a sealing device for a packaging material, such as a standing pouch, a pillow package, a blister package, and a tube to be used for a refill, made of a single layer plastic sheet, and a laminated plastic sheet. The present invention also relates to a measuring method for fusion temperature of plastics, such as a sealing temperature of a plastic sheet comprising a packaging material such as a standing pouch, and a tube.
2. Background Art
A packaging material comprising plastic sheets is used for sealing by overlapping layers to be sealed (sealant layers) of the plastic sheets facing with each other, and pressuring the same with a sealing bar (mold) such as a heat sealing bar from the outside so as to press and fuse the layers to be sealed in a melting temperature state.
(A) In conventional sealing devices, it comprises either a surface sealing device for pressuring layers of plastic sheets to be sealed with a seal bar of a width necessary for sealing by the plastic sheet sealing width so as to press the layers to be sealed in a melting state, and a cooling sealing device disposed subsequent thereto, for pressuring the layers to be sealed of the plastic sheets, pressed by the surface sealing device with a cooling sealing bar so as to cool and solidify the pressed state of the layers to be sealed.
However, the conventional technique involves the following problems.
(1) It is difficult to pressure the entire area of the layers of the plastic sheets to be sealed with a sealing bar stably by a high pressure in the surface sealing device or the cooling sealing device. At a part with a weak pressure, entanglement of the plastic cannot be produced sufficiently, and thus the risk of sealing failure is involved. If a high pressure is provided to the entire area, the layers to be sealed are deformed so that a necessary thickness cannot be retained.
(2) If a liquid (filling content of the packaging material) or a highly viscous product thereof is adhered on the layers of the plastic sheets to be sealed, the sealing operation is executed with the liquid disposed between the layers to be sealed, and thus the risk of sealing failure is involved.
An object of the present invention is to certainly press and seal layers of plastic sheets to be sealed, facing each other.
(B) Moreover, as to the sealing temperature administration for a plastic sheet in the conventional production of a packaging material, merely the heat sealing bar surface temperature and the surface temperature of the layers to be sealed or the plastic sheets are measured with a contact type thermometer or a non-contact type thermometer (infrared ray thermometer, or the like), but the temperature of the sealant material at the time of actually fusing is not measured.
However, according to the knowledge of the present inventors, in order to certainly fuse the plastic sheets, the temperature of the layers of the plastic sheets to be sealed should be an extrapolated melting end temperature or more, higher than the melting peak temperature of the plastic, and thus the temperature of the layers to be sealed (sealant material) should be administered accurately. With a temperature lower than the extrapolated melting end temperature, although a part of the molecular weight of the plastic comprising the layers to be sealed is melted , a molecular weight side is not melted so that an unstable sealing may be provided.
An object of the present invention is to accurately measure the temperature of the sealant material at the time of actually fusing the plastic. The extrapolated melting end temperature will be explained in an embodiment.
An object of the present invention is to accurately measure the temperature of the sealant material at the time of actually fusing the plastic sheet comprising a packaging material, or the like.
(A) The present invention provides a sealing device for a packaging material for overlapping layers of plastic sheets to be sealed, facing each other, pressuring the same from the outside with a sealing bar, and pressing the layers to be sealed in a melting state by a predetermined sealing width so as to be sealed, comprising a linear sealing device for pressuring the layers of the plastic sheets to be sealed, the layers of plastic sheets being pressured with a sealing bar having a width narrower than the sealing width, and pressuring the layers to be sealed in a heated state, and a surface sealing device disposed subsequent to the linear sealing device, for pressuring the layers to be sealed including the part pressured by the linear sealing device with a sealing bar having a width necessary for sealing by a sealing width, and pressing the layers to be sealed in a melting state.
(B) Moreover, the present invention is for measuring the temperature with a temperature measuring contact comprising a thermometer mounted on a fused part of a plastic.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.